Integrated Study of the Calcination Cycle from Gibbsite to Corundum

Hill, Matthew R.; Bastow, Timothy J.; Celotto, S.; Hill, Anita J.

doi:10.1021/cm070078f

Cited by 52 publications

(49 citation statements)

References 34 publications

(69 reference statements)

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“…[49] In Fig. 5 we compare the theoretical spectra with the experimental data by O' Dell et al 19 (left panel, 14.1 T), and by Hill et al 18 (right panel, 9.4 T). We also compared with the 9.4 T spectrum by Pecharromán et al 55 (not shown) which agrees very well with the one by Hill et al.…”

Section: Fig 3 (Color On-line) Comparison Between the Experimentalmentioning

confidence: 86%

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Ab initio27Al NMR chemical shifts and quadrupolar parameters for Al2O3phases and their precursors

et al. 2011

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The Gauge-Including Projector Augmented Wave (GIPAW) method, within the Density Functional Theory (DFT) Generalized Gradient Approximation (GGA) framework, is applied to compute solid state NMR parameters for 27 Al in the α, θ, and κ aluminium oxide phases and their gibbsite and boehmite precursors. The results for well-established crystalline phases compare very well with available experimental data and provide confidence in the accuracy of the method. For γ-alumina, four structural models proposed in the literature are discussed in terms of their ability to reproduce the experimental spectra also reported in the literature. Among the considered models, the F d3m structure proposed by Paglia et al. [Phys. Rev. B 71, 224115 (2005)] shows the best agreement. We attempt to link the theoretical NMR parameters to the local geometry. Chemical shifts depend on coordination number but no further correlation is found with geometrical parameters. Instead our calculations reveal that, within a given coordination number, a linear correlation exists between chemical shifts and Born effective charges.

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Section: Fig 3 (Color On-line) Comparison Between the Experimentalmentioning

confidence: 86%

“…4 27 Al MAS NMR spectra from Ref. [18] for gibbsite and the theoretical spectrum obtained with the vdW-DF functional. Decomposition of the spectrum in individual components is also given.…”

Section: Gibbsite and Boehmite Phasesmentioning

confidence: 99%

Ab initio27Al NMR chemical shifts and quadrupolar parameters for Al2O3phases and their precursors

et al. 2011

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“…In that case, dehydration of these hydrates would also contribute, although in small amount, to this LC [23]. The component at 297.3 ºC, representing a 3.0 %, should be assigned to gibbsite dehydroxylation [24,21]. As it was described for ungrounded samples [24], a further gradual weight loss could be completed by 700 ºC overlapping with other processes.…”

Section: Resultsmentioning

confidence: 95%

“…The 128 and 188 ºC LC account for almost a 3.5 % and can be easily assigned to gypsum and bassanite dehydration, which were identified by XRD [19,20]. The 254 ºC component, accounting for an 8.7 % of the weight loss, might have been contributed by evolved water from particle surfaces during the transition from gibbsite to boehmite since it was reported to take place in a range around 247 ºC [21,22]. According to Table 1, small amounts of magnesium carbonate hydrates may exist.…”

Section: Resultsmentioning

confidence: 99%

Lodos procedentes de la industria de tratamiento de superficies metálicas como aditivos a matrices cerámicas

Corpas-Iglesias¹,

Pérez‐Villarejo²,

Guerrero³

et al. 2011

Bol. Soc. Esp. Ceram. Vidr.

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Ceramic processing is one of the most efficient and environmentally friendly solutions to the enormous amounts of industrial mud produced in metal surface treatments. Moreover, ceramized products may represent an important secondary source to replace clay materials and cut down manufacturing costs. After characterization, in order to prepare specimens by uniaxial die pressing, mud was incorporated into a clay matrix at rates between 1 and 5 wt %. Compression strength, linear contraction, suction capacity and water absorption of the moulded materials were evaluated. Finally, metal leakage was characterized through chemical analysis of lixiviates. The results showed an improvement in mechanical properties following the incorporation of mud into the ceramic materials. The resulting materials meet health and safety regulations regarding dangerous waste recycling.Keywords: Valorization, Mud, Ceramic, Waste. Lodos procedentes de la industria de tratamiento de superficies metálicas como aditivos a matrices cerámicasLa ceramización es una de las soluciones más eficientes y medioambientalmente más ecológicas para las enormes cantidades de lodos industriales que se producen en el tratamiento de superficies metálicas. Además estos lodos convenientemente ceramizados pueden representar una fuente de materia prima que sustituya en parte el consumo de arcilla, lo que se traduce en una disminución de los costes de fabricación. Tras caracterizarse, los lodos fueron incorporados en la matriz cerámica en proporciones desde el 1% hasta el 5%, fabricándose así piezas cerámicas por compresión uniaxial en seco. A las piezas conformadas se les midieron una serie de características tecnológicas tales como la resistencia a la compresión, la contracción lineal, capacidad de succión y la absorción de agua. Finalmente se realizaron análisis químicos de lixiviados para evaluar la liberación al medio de metales. Los resultados conseguidos muestran una mejora de las propiedades mecánicas tras la inclusión de los lodos en matrices cerámicas. Los materiales así fabricados satisfacen la normativa referente al reciclaje de residuos peligrosos.

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“…The results show large changes in structure at calcination temperatures between 200 and 300 • C. Large changes in structure are also thought to occur in the range 900 to 1000 • C. Weller 17) and Peri 18) report that water molecules dissociatively adsorb onto aluminum oxide; dissociative adsorption has also been reported for boehmite. 19) The phases from GB to corundum by calcination were reported by Hill et al 20) Table 1 shows the relationship between GB calcination temperature and the specific surface area, the surface pH and the concentration of surface hydroxyl groups. In these results, the specific surface area increased greatly at a calcination temperature of 300 • C, reached a maximum at a calcination temperature of 400 • C, and then decreased as the calcination temperature rose.…”

Section: Methodsmentioning

confidence: 98%

Relationship between Anion Adsorption and Physicochemical Properties of Aluminum Oxide

Kawasaki

Ogata

Takahashi

et al. 2008

JOURNAL OF HEALTH SCIENCE

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This study investigated the adsorption capacity and adsorption mechanism of phosphate by calcined aluminum oxide (GB) at temperatures of 200 to 1150• C. The results showed that GB and GB calcined at a temperature of 200• C exhibited almost no adsorption capacity, and GB calcined at temperatures of 300 or 400• C exhibited the highest adsorption capacity. After that, adsorption capacity tended to decrease with increasing calcination temperature. The specific surface area and the concentration of surface hydroxyl groups exhibited the highest values in GB calcined at temperatures of 300 and 400• C. From the above facts, it is conjectured that the specific surface area and concentration of surface hydroxyl groups contribute to the adsorption of phosphate in calcined GB.The results of X-ray diffraction showed that the structure of GB changed drastically at temperatures of 200 to 300• C and 900 to 1000 • C. Also, it was evident that phosphate was adsorbed selectively even in complex solution systems containing chloride, nitrate, sulfate, hydrogen carbonate and phosphate ions, and that calcined GB is suitable for adsorption of phosphate. For the adsorption of phosphate, it was found that the optimum pH is around 4. When calcined GB is suspended in purified water, it is thought that hydroxyl groups form through dissociative adsorption with water molecules, and that these hydroxyl groups conduct ion exchange with phosphate.

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Integrated Study of the Calcination Cycle from Gibbsite to Corundum

Cited by 52 publications

References 34 publications

Ab initio27Al NMR chemical shifts and quadrupolar parameters for Al2O3phases and their precursors

Ab initio27Al NMR chemical shifts and quadrupolar parameters for Al2O3phases and their precursors

Lodos procedentes de la industria de tratamiento de superficies metálicas como aditivos a matrices cerámicas

Relationship between Anion Adsorption and Physicochemical Properties of Aluminum Oxide

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